Adding a background color to blog posts / or color each post with a white background.

Hi

I want the blog and calendar posts to have a background color distinct from the page background. Or have a box around them to show where one starts and the next begins.  

I see how it was done with blocks .  
Adding a background color to blocks and sections of website.

but not how it is done in a posts page or a calendar etc. 

Hi. Can you share link to blog? We can help easier